grub_prefix seems wrong for separate /boot partition

grub_prefix seems wrong for separate /boot partition

[Christoph Mathys]

Hello

Not sure if I've come to the right place, but here is my story:

Yesterday, my package manager (deb on testing) decided that the time has 
come to switch to grub 1.97~beta3. Well, afterwards my system did not 
boot anymore, it was stuck in the grub shell, no menu or anything. It 
works again now and I quiet like the new grub shell (well, scrolling was 
horribly slow).

Anyway, my /boot-directory is on its own partition, which is only 
mounted if I need to change something there. Now, one of the problems 
why the update did not work was that I forgot to mount /boot and grub 
could not find the kernels (my fault).

After I've learned how to boot my system again and mounted /boot, grub 
found the kernels. However, grub_prefix seems to be wrong, pointing to 
/boot/grub instead of just /grub. I did not find a better way to fix it 
than changing the variable in grub-install. After changing grub_prefix 
to /grub and rerunning grub-install /dev/hda, everything is fine now.

Maybe grub_prefix should be setable on the command line of grub-install? 
  Or some other bad mistake on my part because of scoping the amount of 
documentation I read using google?

Christoph

Re: grub_prefix seems wrong for separate /boot partition

[Felix Zielcke]

Am Donnerstag, den 01.10.2009, 23:29 +0200 schrieb Christoph Mathys:
> Hello
> 
> Not sure if I've come to the right place, but here is my story:
> 
> Yesterday, my package manager (deb on testing) decided that the time has 
> come to switch to grub 1.97~beta3. Well, afterwards my system did not 
> boot anymore, it was stuck in the grub shell, no menu or anything. It 
> works again now and I quiet like the new grub shell (well, scrolling was 
> horribly slow).
> 
> Anyway, my /boot-directory is on its own partition, which is only 
> mounted if I need to change something there. Now, one of the problems 
> why the update did not work was that I forgot to mount /boot and grub 
> could not find the kernels (my fault).
> 
> After I've learned how to boot my system again and mounted /boot, grub 
> found the kernels. However, grub_prefix seems to be wrong, pointing to 
> /boot/grub instead of just /grub. I did not find a better way to fix it 
> than changing the variable in grub-install. After changing grub_prefix 
> to /grub and rerunning grub-install /dev/hda, everything is fine now.
> 
> Maybe grub_prefix should be setable on the command line of grub-install? 
>   Or some other bad mistake on my part because of scoping the amount of 
> documentation I read using google?

It should be never needed to change grub-install to fix this.
If /boot is a seperate partition then the prefix gets just /grub.
If not then it's a bug. And in that case the generated grub.cfg has the
same problem.
This is actually impossible that only grub-install but not grub-mkconfig
was affected in your case. They use both the same function to make it
relative to the root.
Did you run grub-install again after you mounted your /boot or did you
just copy the files?

-- 
Felix Zielcke
Proud Debian Maintainer and GNU GRUB developer

Re: grub_prefix seems wrong for separate /boot partition

[Christoph Mathys]

Felix Zielcke wrote:
> Am Donnerstag, den 01.10.2009, 23:29 +0200 schrieb Christoph Mathys:
>> Maybe grub_prefix should be setable on the command line of grub-install? 
>>   Or some other bad mistake on my part because of scoping the amount of 
>> documentation I read using google?
> 
> It should be never needed to change grub-install to fix this.
> If /boot is a seperate partition then the prefix gets just /grub.
> If not then it's a bug. And in that case the generated grub.cfg has the
> same problem.
> This is actually impossible that only grub-install but not grub-mkconfig
> was affected in your case. They use both the same function to make it
> relative to the root.
> Did you run grub-install again after you mounted your /boot or did you
> just copy the files?

I guess I just copied the files. You are right, mounting boot and 
running the following commands results in the correct configuration 
without twiddling on the scripts:
'grub-install /dev/hda'
'grub-mkconfig -o /boot/grub/grub.cfg'

Thanks for the pointer!
Christoph